Data of piezoelectric vibration energy harvesting of a bridge undergoing vibration testing and train passage.

The data presented in this article is in relation to the research article "Vibration energy harvesting based monitoring of an operational bridge undergoing forced vibration and train passage" Cahill et al. (2018) [1]. The article provides data on the full-scale bridge testing using piezoelectric vibration energy harvesters on Pershagen Bridge, Sweden. The bridge is actively excited via a swept sinusoidal input. During the testing, the bridge remains operational and train passages continue. The test recordings include the voltage responses obtained from the vibration energy harvesters during these tests and train passages. The original dataset is made available to encourage the use of energy harvesting for Structural Health Monitoring.

Disposable sensor based on enzyme-free Ni nanowire array electrode to detect glutamate.

Enzyme free electrochemical sensor platform based on a vertically aligned nickel nanowire array (NiNAE) and Pt coated nickel nanowire array (Pt/NiNAE) have been developed to detect glutamate. Morphological characterisation of Ni electrodes was carried out using scanning and transmission electron microscopy combined with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNAE and the Pt/NiNAE for glutamate. It has been found that both NiNAE and Pt/NiNAE electrodes showed remarkably enhanced electrocatalytic activity towards glutamate compared to planar Ni electrodes, and showed higher catalytic activity when compared to other metallic nanostructure electrodes such as gold nanowire array electrodes (AuNAE) and Pt coated gold nanowire array electrode (Pt/AuNAE). The sensitivity of NiNAE and Pt/NiNAE has been found to be 65 and 96 µA mM(-1) cm(-2), respectively, which is approximately 6 to 9 times higher than the state of the art glutamate sensor. Under optimal detection conditions, the as prepared sensors exhibited linear behaviour for glutamate detection in the concentration up to 8mM for both NiNAE and Pt/NiNAE with a limit of detection of 68 and 83 µM, respectively. Experimental results show that the vertically aligned ordered nickel nanowire array electrode (NiNAE) has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform.

Ultra-long metal nanowire arrays on solid substrate with strong bonding.

Ultra-long metal nanowire arrays with large circular area up to 25 mm in diameter were obtained by direct electrodeposition on metalized Si and glass substrates via a template-based method. Nanowires with uniform length up to 30 µm were obtained. Combining this deposition process with lithography technology, micrometre-sized patterned metal nanowire array pads were successfully fabricated on a glass substrate. Good adhesion between the patterned nanowire array pads and the substrate was confirmed using scanning acoustic microscopy characterization. A pull-off tensile test showed strong bonding between the nanowires and the substrate. Conducting atomic force microscopy (C-AFM) measurements showed that approximately 95% of the nanowires were electrically connected with the substrate, demonstrating its viability to use as high-density interconnect.

Investigation into the effect that probe immobilisation method type has on the analytical signal of an EIS DNA biosensor.

The analytical performance of an enhanced surface area electrolyte insulator semiconductor (EIS) device was investigated for DNA sensor development. The work endeavored to advance EIS performance by monitoring the effect of DNA probe layers have on the impedimetric signal during target hybridisation detection. Two universally employed covalent chemistries, direct and spacer-mediated attachment of amino modified probe molecules to amino-functionalised surfaces were investigated. Relative areal densities of immobilised probe were measured on planar and enhanced surface area substrates using epi-fluorescence microscopy. The reproducibility of the each immobilisation method was seen to have a direct effect on the reproducibility of the impedimetric signal. The sensitivity and selectivity was seen to be dependent on the type of immobilisation method. Real time, impedimetric detection of target DNA hybridisation concentrations as low as 25 and 1 nM were possible. The impact that probe concentration had on the impedimetric signal for selective and non-selective interactions was also investigated.

Microporous silicon and biosensor development: structural analysis, electrical characterisation and biocapacity evaluation.

An investigation of the fabrication of microporous silicon (MPS) layers as a material for the development of an electrolyte insulator semiconductor (EIS) capacitance sensor has been performed. The goal was to create a high surface area substrate for the immobilisation of biorecognition elements. Structural analysis of MPS layers as a function of key etch parameters, namely implant type (p or n), implant dose, hydrofluoric acid (HF) etch concentration and current density has been performed using scanning electron microscopy (SEM). It was possible to image porous layers with average pore diameter as low as 4 nm. n-type silicon samples had larger pore networks than p-type samples and reducing the silicon resistivity led to a reduction in the pores per microm2. It was found that increasing the HF etch concentration reduced the average pore diameter and increased the pores per microm2. Increasing the current density at which the etch was performed has the same effect. Understanding the effect of these parameters allows the MPS layer to be tuned to match specifications for optimum biocapacity. Different MPS layers were electrically characterised using capacitance-voltage and capacitance-frequency sweeps, in order to determine the effect of porosity on increases in surface area. The measured capacitance increased with increasing pores per microm2. p-type silicon with a boron implant in the back of the wafer, which had been etched in 25% HF in ethanol at a current density of 75 mA/cm2 yielded the highest capacitance signal per unit area. The effect of porosity and pore size on the biocapacity of the samples was also determined. For avidin immobilisation, with pores sizes above 5 nm, as the porosity increased the biocapacity increased. MPS fabricated in p-type silicon with a front and back implant etched in 25% HF at a current density of 25 mA/cm2 was used for the capacitance detection of synthetic oligonucleotides.

Application of magnetohydrodynamic actuation to continuous flow chemistry.

Continuous flow microreactors with an annular microchannel for cyclical chemical reactions were fabricated by either bulk micromachining in silicon or by rapid prototyping using EPON SU-8. Fluid propulsion in these unusual microchannels was achieved using AC magnetohydrodynamic (MHD) actuation. This integrated micropumping mechanism obviates the use of moving parts by acting locally on the electrolyte, exploiting its inherent conductive nature. Both silicon and SU-8 microreactors were capable of MHD actuation, attaining fluid velocities of the order of 300 microm s(-1) when using a 500 mM KCl electrolyte. The polymerase chain reaction (PCR), a thermocycling process, was chosen as an illustrative example of a cyclical chemistry. Accordingly, temperature zones were provided to enable a thermal cycle during each revolution. With this approach, fluid velocity determines cycle duration. Here, we report device fabrication and performance, a model to accurately describe fluid circulation by MHD actuation, and compatibility issues relating to this approach to chemistry.